About

Xray Vision, part I

As an art conservation student, I was frequently encouraged by my tutors to think of my profession as a three-legged stool—a platform supported by the three disciplines of connoisseurship, fine arts, and science. Understanding the science of how materials age is critical for being able to slow down deterioration. In addition, scientific methods of analysis can inform our understanding of how an object was made, when it was made, or where it came from. For me, this kind of investigation is one of the most fun and interesting parts of my job. This past week I used Xray energy, produced by two different pieces of equipment in different ways, to find out more about objects in Te Papa’s collection. This post describes the use of a non-invasive scanner to study a taiaha (long club fighting staff). In a subsequent post I will talk about a new piece of equipment in our lab called XRF.

The taiaha was purchased by the museum in 1905, and is thought to be about 200 years old. It has a decorative band (tauri) of red wool textile stitched at the top, but it’s evident from the shape and bulk of the tauri that the wool is covering other soft material. When I first examined the taiaha, I was intrigued. Other textile wrappings that I’ve seen on taiaha aren’t stitched, they’re wrapped, and examples with dog hair tassels often have feather adornment as well. Was the wool covering feathers, or many layers of other wrappings? Proceeding with the assumption that the red wool was an historically important part of the object and not a restoration treatment, I did not strip it off to satisfy my curiosity! Instead, I investigated the possibility of having the object Xrayed. Te Papa does not (yet!) have digital Xray capability, and tikanga (cultural protocol) considerations ruled out Wellington Hospital. So, it was off to the National Isotope Laboratory at GNS, in Lower Hutt.

Te Papa’s Kaitiaki Taonga Māori Shane James and Objects Conservator Nirmala Balram working with Karyne Rogers and John West at the GNS Isotope Centre. Image by Anne Peranteau, copyright Te Papa.

At GNS, we worked with Karyne Rogers and John West to obtain an Xray image of the taiaha using a non-invasive Xray scanner, of the type that is commonly used in airports. The scanner provides an image that indicates the relative density of the materials being scanned—orange for low density organic material, green for medium density material, and blue for high density material. Have you ever wondered what the airport security personnel see on their screen when your bag goes on the belt? This gives you some idea.

From the image we were able to conclude that the material below the red wool is a higher density material, applied in two wide bands. Raupo or muka were two possibilities put forward by Objects Conservator Nirmala Balram and Kaitiaki Taonga Māori Shane James. The wrappings below the red wool are not woven cloth, nor are feathers present.

The taiaha will be included in an upcoming Te Papa exhibition called Uniformity: Cracking the Dress Code, scheduled to open in September. Shane will be working with GNS to do more scanning of putorino (flutes) and other musical instruments, to learn more about the construction of these objects, and particularly their interior dimensions in relationship to the sounds they make.